This hidden green space is the city's second largest conservatory.

Rebuilt remains of a temple to Roman god Mithras.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the first ‘Harry Potter’ film.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

This one has sailed five times as far as Sir Francis Drake's famous ship.

The handiwork of a underdog clockmaker who solved an impossible problem for an Empire, and forever revolutionized seafaring.

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

This unassuming alcove in London’s famous Tower Bridge once served to capture, store, and display dead bodies from the River Thames.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Graffiti from the 16th and 17th centuries cover the walls of this part of the Tower of London.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

These wire animal sculptures commemorate the exotic inhabitants that once called the Tower of London home.

A memorial for public executions that dates back to the 14th century.

One of several Lilliputian portals that are ready to transport passengers to other dimensions, if they can find them.

Modern commuters still pass through this 2,000-year-old Roman archway.

Legend says this demonic carving inside a medieval cathedral was one of Satan's minions.

Inside this chapel, Victorian jailers took the separate system to new levels.

The oldest of the three remaining bridges in England with buildings on top of them.

A Reformation-era fiery figurehead once denoted this location as a print shop.

Semaphore saints, a golden dragon's head, and a stone carved with religious warnings all call this cathedral home.

This memorial to World War II's fallen airmen shows us the movements of the stars that once guided them.